Dog Health Questions? Ask a Dog Vet for Answers ASAP
Tough to say.
Either there was already a urinary tract infection, or prepucial infection (infection of the sheath surrounding the penis (right where it pops out), or the licking caused the problem in the first place.
Treatment will definitely require going into a vet to examine the tip of the penis and the sheath, and likely, some oral antibiotics to go home.